Cross-sectional Layout Research Articles

A new cross-section layout method and geometrical parameter optimization for floor beams of rack car body considering modal factors

A new cross-section layout method and geometrical parameter optimization for floor beams of rack car body considering modal factors

Cross-sectional layout optimization of the umbilical based on the quasi-physical algorithm

Umbilical, as the lifeline of offshore oil and gas resources exploitation, is composed of a variety of functional components. Due to the differences in physical characteristics of components, the compactness, balance and heat source dispersion of different cross-sectional layouts are also different. So, a multi-objective optimization problem is often encountered. In present study, through a quasi-physical method, different functional components are abstracted as the virtual spheres with different properties lied on a funnel surface. A mathematical description is thereby established according to the interaction force of each two neighbored virtual spheres. Based on that, a new cross-sectional layout optimization formulation is proposed, and solved by using the quasi-physical algorithm. Considering the manufacturing and installation, a layered method is utilized to make the results more in line with the actual needs of the project. Finally, the optimization results of the method are verified by numerical simulation. The verification results show that the cross-sectional layout optimization method based on a quasi-physical algorithm can provide a useful reference for practical engineering design.

Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Thermo-mechanical numerical analyses in support of fire endurance assessment of ordinary soda-lime structural glass elements

PurposeGlass material is largely used for load-bearing components in buildings. For this reason, standardized calculation methods can be used in support of safe structural design in common loading and boundary conditions. Differing from earlier literature efforts, the present study elaborates on the load-bearing capacity, failure time and fire endurance of ordinary glass elements under fire exposure and sustained mechanical loads, with evidence of major trends in terms of loading condition and cross-sectional layout. Traditional verification approaches for glass in cold conditions (i.e. stress peak check) and fire endurance of load-bearing members (i.e. deflection and deflection rate limits) are assessed based on parametric numerical simulations.Design/methodology/approachThe mechanical performance of structural glass elements in fire still represents an open challenge for design and vulnerability assessment. Often, special fire-resisting glass solutions are used for limited practical applications only, and ordinary soda-lime silica glass prevails in design applications for load-bearing members. Moreover, conventional recommendations and testing protocols in use for load-bearing members composed of traditional constructional materials are not already addressed for glass members. This paper elaborates on the fire endurance and failure detection methods for structural glass beams that are subjected to standard ISO time–temperature for fire exposure and in-plane bending mechanical loads. Fire endurance assessment methods are discussed with the support of Finite Element (FE) numerical analyses.FindingsBased on extended parametric FE analyses, multiple loading, geometrical and thermo-mechanical configurations are taken into account for the analysis of simple glass elements under in-plane bending setup and fire exposure. The comparative results show that – in most of cases – thermal effects due to fire exposure have major effects on the actual load-bearing capacity of these members. Moreover, the conventional stress peak verification approach needs specific elaborations, compared to traditional calculations carried out in cold conditions.Originality/valueThe presented numerical results confirm that the fire endurance analysis of ordinary structural glass elements is a rather complex issue, due to combination of multiple aspects and influencing parameters. Besides, FE simulations can provide useful support for a local and global analysis of major degradation and damage phenomena, and thus support the definition of simple and realistic verification procedures for fire exposed glass members.

Study on the automatic optimization design of the cross-sectional layout of an umbilical with layers based on the GA-GLM

Marine umbilical provides the remote control function for offshore oil and gas exploitation, which is usually integrated by different functional components that vary widely in their mechanical properties. Under the action of external load, unreasonable cross-sectional layouts may lead to large cross-sectional deformation and contact pressure between components thus affecting the service life of an umbilical. Therefore, how to design the cross-sectional layout is a very necessary research work in order to improve service life of the umbilical to withstand various loads during operation. At present, the research on the cross-sectional layout of an umbilical is not sufficient, and there is no standardized design method in the design specification. Considering the mechanical and geometrical properties as the quantitative design objectives, the mathematical optimization model of the cross-sectional layout of an umbilical is proposed. Meanwhile, the layering strategy is introduced because of the processing and manufacturing factors.Then, the genetic algorithm (GA) with good global search performance and the generalized Lagrange multiplier (GLM) with fast convergence speed are combined to solve the above model. Finally, taking an umbilical as an example, the optimal cross-sectional layout is obtained and the effectiveness of the algorithm is verified by the numerical simulation. The results show that the optimization method proposed in this paper can quickly obtain the optimal design cross-sectional layout, and supply a specific way for the fast design of an umbilical, which has the certain engineering application value.

Compressive Behaviour of Square CFDST Short Columns with Double Inner Steel Tubes

This study focuses on the experimental analysis of concrete-filled double-skin tubular (CFDST) short columns with double circular inner steel tubes under concentric axial loading. This cross-section layout promises to increase the ductile behavior of the compressive element and its energy absorption capacity, not to mention its ultimate axial strength. This research analyses main twofold variables: (i) Hollow ratio and (ii) eccentricity ratio (i.e., distance ratio between the inner tube’s separation and the sandwiched concrete width). As a result, load Vs. Axial deformation, load Vs. Axial strain curves, ductility index, strength index, energy absorption capacity, and ultimate axial capacity formulae for square CFDST columns with double circular inner tubes are reported. Key findings of this study show that (a) ductility is an intrinsic property of these types of sections; (b) the variation effect of hollow ratio influence inversely in the confined concrete strength of the element, (c) Eccentricity ratio has proved to be the least ultimate strength capacity influencer. However, its impact increases when it is jointly analyzed with the hollow ratio values. (d) The formulae proposed for predicting the ultimate capacity of CFDST columns showed good agreement with the experimental results. Thus, these expressions could be extended to the design of composite CFDST elements, provided a resistance factor based on a reliability analysis is incorporated.

Research on the effect of micron-groove orifices on the static characteristics of aerostatic journal bearings under high gas supply pressures based on the SST k-ω turbulence model

To improve the static characteristics of orifice-compensated aerostatic journal bearings (OCAJBs) under high gas supply pressures, governing equations considering inertial forces are established based on the shear stress transport (SST) k- ω turbulence model, and a double-row gas supply micron-groove orifice aerostatic journal bearing (MGOAJB) is designed. The influences of the structural parameters of the micron-groove orifice (MGO), such as the groove cross-sectional shape, dimensional parameters and layout, on the static characteristics under high gas supply pressures are studied. The SST k- ω turbulence model can accurately simulate the pressure distribution of a gas film flow field under high gas supply pressures, and the MGO can effectively improve static bearing characteristics such as the load capacity and stiffness. The influences of the groove cross-sectional shape, groove depth, and groove width of the MGO are not significant, but the groove length, orifice diameter, and MGO layout have obvious impacts on the load capacity and stiffness of a bearing. Structural parameters should be reasonably selected in the bearing design process.

SOCIODEMOGRAPHIC ASPECTS OF CONTRACEPTION USE IN KAMPUNG KB KOTA YOGYAKARTA

Background: One of the government's efforts to control the population growth rate is to reduce the birth rate through the family planning program by utilizing the contraceptive method.This study aims to analyze the factors that influence contraceptive use at Kampung KB in Yogyakarta Method: It belongs to obsvational research with cross sectional layout using quantitative approach. Sampling was performed using Accidental Random Sampling.Collecting data using online quitioner that was shared to women in reproductive years in all Kampung KB. Data processing using STATA version 14. The data analysis was performed gradually covering univariable analysis, bivariable. Result: Age, education, desire to have children, parity, knowledge and attitudes have the pto increase contraceptive use, while economic level is not positively related to contraceptive use.The reasons for not using contraception are lack of permission from a partner and external environmental pressure. Conclusion: Sociodemographic aspects have the opportunity to increase contraceptive use at Kampung KB in Kota Yogyakarta.

Study on the optimization algorithm of the cross-sectional layout of an umbilical based on the layering strategy

As a key device in subsea production system of the offshore hydrocarbon resources exploitation, the umbilical consists of a variety of functional components such as hydraulic tubes, electrical cables and optical cables. The cross-sectional layout design plays an important role in the performance of an umbilical. Considering the mechanical and geometrical properties as the quantitative design objectives, the mathematical model of multi-objective optimization of the cross-sectional layout of an umbilical is described. Meanwhile, the algorithm of smallest radius of the enclosing circle and the multiplier penalty function method are proposed. Then, the manufacture factor is considered and the layering strategy based on the identification of contact points is introduced to modify implement algorithm to obtain the optimal cross-sectional layout with layering characteristic. Finally, some case studies are performed, the optimal cross-sectional layouts with layering characteristic are obtained. Comparing with the initial design and cross-sectional layouts without layering, the results verify the feasibility of the presented optimization design algorithm, which can improve the design efficiency of an umbilical and avoid the manual process.

Fundamental Electromagnetic Configuration for Generating One-Directional Magnetic Field Gradients

In this article, electromagnet layouts are presented, which generate a magnetic field with a magnitude gradient that does not vary significantly in a horizontal plane but decreases monotonically with the vertical height above the magnet. Such a one-direction magnetic field gradient is a specific requirement for magnetic density separation (MDS), a novel recycling technology that combines a vertical magnetic field gradient with a ferrofluid to separate a mixture of non-magnetic materials based on their mass density. We are assembling the first superconducting magnet to be used for this application. In contrast to other separation technologies that use ferrofluid, multiple products can be separated in a single process step. First, the idealized current distribution is introduced that produces such a magnetic field with a magnitude that decays only in one direction. This ideal field can be approximated with practical coil configurations, which are evaluated with a Fourier analysis to derive an optimal cross-sectional layout based on flat racetrack coils. The analysis concludes with a discussion of the effect of winding pack thickness on the value of the magnetic field above the magnet system and the peak field inside the winding pack. The conclusions of this study are applicable not just for MDS but for any application that requires a magnetic field gradient that changes only in one direction.

Toward REBCO 20 T+ Dipoles for Accelerators

ReBCO high temperature superconducting (HTS) coated conductor tapes are a promising candidate for pushing the magnetic fields in accelerator magnets well beyond 20 T. They are capable of very high current densities in intense applied magnetic field, have a very high thermal stability, can withstand high transverse pressures and allow operation in 20-30 K helium gas flow, potentially reducing operating cost significantly. During the EuCARD2 program, significant developments have been made in terms of coil design, manufacturing, and testing. Now that EuCARD2 has come to an end, CERN and collaborators are initiating a new program to continue the development of HTS accelerator magnets. This paper presents our initial thoughts on the conceptual design of a 20 T+ accelerator magnet, using the results and technologies from EuCARD2 combined with some new ideas. The paper discusses the options available for the cross-sectional layout, the use of a hybrid configurations, including Aligned Block, the design of the coil-ends and dual aperture configurations. Also, discussed is the quench protection of the magnets. Due to the high thermal stability of the conductor and high energy densities, it will be required to explore an entirely a new approach.

Pareto-Optimization of HTS CICC for High-Current Applications in Self-Field

The ENEA superconductivity laboratory developed a novel design for Cable-in-Conduit Conductors (CICCs) comprised of stacks of 2nd-generation REBCO coated conductors. In its original version, the cable was made up of 150 HTS tapes distributed in five slots, twisted along an aluminum core. In this work, taking advantage of a 2D finite element model, able to estimate the cable’s current distribution in the cross-section, a multiobjective optimization procedure was implemented. The aim of optimization was to simultaneously maximize both engineering current density and total current flowing inside the tapes when operating in self-field, by varying the cross-section layout. Since the optimization process involved both integer and real geometrical variables, the choice of an evolutionary search algorithm was strictly necessary. The use of an evolutionary algorithm in the frame of a multiple objective optimization made it an obliged choice to numerically approach the problem using a nonstandard fast-converging optimization algorithm. By means of this algorithm, the Pareto frontiers for the different configurations were calculated, providing a powerful tool for the designer to achieve the desired preliminary operating conditions in terms of engineering current density and/or total current, depending on the specific application field, that is, power transmission cable and bus bar systems.

Layout Study for the Dipole Magnets of the Future Circular Collider Using Nb-Ti and Nb3Sn

With the Large Hadron Collider (LHC) up and running, studies have started for its successor. Under study is the Future Circular Collider (FCC), which has a circumference of about 100 km, aiming at a proton-proton collision energy of 100 TeV. Consequently, the main bending dipole magnets have to operate at a magnetic field of 16 T. As a first step towards its realization, this paper presents the results of a parametric study of the cross-sectional layout for dipole magnets with a field in the range of 13-17 T using Nb-Ti and Nb3Sn superconductors. The principal layouts included are the classical Cosine-Theta, the Canted Cosine-Theta, and the Block type. Conductor cost can be reduced significantly when a graded hybrid solution is chosen. Optimizing such complex magnet layouts requires an iterative algorithm, which arranges the positions of the various blocks of coil windings in the coil cross section, thereby finding the thickness of the coil layers. The iterative algorithm is coupled to an adiabatic quench model, which finds an optimal copper-to-superconductor fraction for each of the layers. Outside the iterative cycle, a pattern search algorithm is applied to find a cost optimal distribution of the magnetic field generated by each coil layer.

Single-Point Power-Mooring Composite Cables for Wave Energy Converters

This paper presents the analysis and design of single-point power-mooring cables applied to wave energy converters (WECs). A mooring cable design process is suggested, and effects of cable cross-sectional layout, material selection, and conductor design on cable properties are investigated. The study focuses on cable design and structural material for a long service life. Six designs and four structural materials were studied for a total of 18 different configurations. The materials used for the study included Vectran HS, Kevlar 49, carbon fibers in a vinyl ester matrix, and MP35N alloy. Cable design had minimal impact on cable properties. Material used and component helical angle exhibited significant impact on cable mechanical properties. Synthetic fiber designs exhibited more desirable mechanical properties and fatigue performance than both carbon fibers in a vinyl ester matrix and MP35N alloy. Wave device heave and cable tension were not affected by cable material.

Hollow fiber modules with ceramic-supported PDMS composite membranes for pervaporation recovery of bio-butanol

The practical application of hollow fiber membranes for pervaporation technology has been received growing attention in recent years. This work reports the development of hollow fiber modules of ceramic-supported polydimethylsiloxane (PDMS) composite membranes applied for pervaporation process. Computational fluid dynamics (CFD) technique was used to simulate and optimize the flow field distribution in the modules with different packing density and cross-section layout. The hollow fiber modules with proposed configurations were fabricated in our lab and evaluated by pervaporation measurement in model butanol aqueous solution and real fermentation broth. The results suggested that the design of packing density and cross-section layout could realize the optimization of module configuration. The optimized module filled with 7 bundles of hollow fiber membranes at a high packing density of 560m2/m3 exhibits a high and stable performance in the real ABE fermentation broth during 120h continuous operation at 40°C. The average total flux was 1000g/m2h and separation factor were 6.4 for ethanol, 22.2 for butanol and 28.6 for acetone, respectively. Our results demonstrated that the hollow fiber modules developed in this work could be competitive candidates for the practical application in pervaporation recovery of bio-butanol.

Current transfer length in multi-filamentary superconducting NbTi and Nb3Sn strands; experiments and models

The current transfer length of multi-filamentary superconducting NbTi and Nb3Sn strands was measured and analyzed. The aim is to understand and quantify the current distribution process between matrix and superconducting filaments occurring at current injection joints or shunting localized interruptions like originated by transverse cracks or high strain, temperature, or magnetic field in filaments. The current transfer length was investigated on two different multi-filamentary Nb3Sn wires and one NbTi wire. Opposite to earlier clarifications, it was found that the current transfer length cannot be simply represented by a single parameter but depends on the ratio of transport current and critical current and the distance from the current injection point or local interruption of the superconducting path in the filamentary zone. With the aid of our numerical 3D multi-filamentary strand model, simulations were performed showing excellent agreement with the experimental data. For broader use, analytical formulae are proposed to determine the current transfer length for multi-filamentary superconductors with complex cross-sectional layout. The increasing current transfer length with the higher injected current and/or along with the distance away from the current injection point is explained by a progressive current penetration, which is caused by the high resistive matrix layers and complex layout. For the experimental results obtained here, the analytical and numerical simulation results show good agreement against the experimentally measured data from the potential-tips along the strand length.

Design of Cross-Sectional Layout of Steel Tube Umbilical

A design method is presented, which aims at the optimal cross-sectional layout of the multilayer steel tube umbilical. The merit of the method is to improve the tension stiffness and the fatigue life of umbilical. An optimization model is developed for arranging each component layer of the layout by considering the symmetry of mechanical performances of components. Finite element analysis (FEA) is carried out to check the contact force and the radial deformation of different layout types and to confirm the optimal layout design.

New Optimization Strategy for Design of Active Twist Rotor

This paper presents the development of a mixed-variable optimization framework for the aeroelastic analysis and design of active twist rotors. Proper tailoring of the blade properties can lead to the maximization of the active twist and the control authority for vibration reduction under operating conditions. Thus, using mathematical optimization, the cross-sectional layout is designed using continuous and discrete design variables for an active composite rotor blade to maximize the dynamic active twist while satisfying a series of constraints on blade cross-section parameters, stiffness, and strength. The optimization framework developed includes the Intelligent Cross-Section Generator as the cross-section and mesh generator, University of Michigan/Variational Asymptotic Beam Sectional analysis code for active cross-sectional analysis, and Rotorcraft Comprehensive Analysis Software for aeroelastic analysis of the active twist rotor blade. The optimization problem is solved using a surrogate-based approach in combination with the Efficient Global Optimization algorithm. In this paper, the results with mixed design variables are obtained with three different techniques and are compared with the results obtained using continuous design variables.

Computational Fluid Dynamics Simulation of Ventilation Effect of a Large Cross-Section Cable Tunnel

The finite element software ADINA was employed in this paper to study the ventilation effect of a large cross-section cable tunnel by using a computational fluid dynamics method. The temperature and ventilation zoning inside a cable tunnel were determined according to the characteristics of the large cross-section cable tunnel. With the ambient tunnel characteristics and tunnel cross-section layout being taken into consideration, a three-dimensional model for large cross-section cable tunnels was established; the computations indicate that the main influential factors of ventilation effect of large cross-section cable tunnels are intake airflow rate, intake air temperature, exhaust airflow rate, ventilation duration, tunnel length, fire door layout, and so on. The average air velocity in the tunnel was about 60 % of the intake airflow rate. The intake air temperature has much impact on tunnel temperature distribution within a range of 30 m away from the tunnel origin, as shown by a significant cooling effect when intake air temperature falls; whereas the intake air temperature has less impact on tunnel temperature distribution beyond 30 m from the tunnel origin.

Design Process for a NbTi Wire With New Specification Objectives: Technical Design Constraints and Optimization of a Wire Layout Considering Critical Current and AC Losses

New ac applications set high requirements for the performance of superconductors. In particular, in particle accelerators, where large magnets are frequently charged and discharged, low ac losses and high stability must be provided. Otherwise, the cooling costs become intolerable, or the reliability cannot be guaranteed. Although the NbTi conductors have been available for a long time, new wire configurations are needed to fulfill new high performance requirements. Development work of a superconducting wire requires adjusting many parameters, such as filament size and zones and the composition of matrix metal. In addition, there are some technical limits for different design parameters due to the manufacturing process. In this paper, we consider the design process and the design parameters and their limitations from the manufacturer's point of view. As a part of this NbTi wire design, the use of numerical ac loss computation and an optimization method is demonstrated in designing of a cross-section layout for minimizing the ac losses and to achieve a high critical current. This optimization method is among the first steps of numerical optimization procedures, which considers the geometrical optimization, and more studies are needed before it could become a method of practical use. However, in such a case, substantial savings in time and costs in a design process of a new wire can be achieved.